The second part of my digital nature photography book begins by talking about how to get a good exposure. This, according to the text, is the first step in becoming a photographer. Exposure is based on light meter readings taken through the lens and transmitted to the camera's computer. It can be controlled by aperture and shutter speed. Histograms are useful in obtaining the best exposure for a particular shot. This tool, which is usually available on all DSLR camera LCD screens, graphs luminescent values of a particular frame and tells you if the sensor has recorded everything within the frame. The book goes into different types of light metering that most DSLRs can accomplish as well. Evaluative/Matrix metering is recommended as your default metering setting because it measures light from multiple points within the frame and uses a real-situation algorithm to accommodate spotlit and backlit scenes. Average metering is useless according to the book. Spot metering bases the light reading on a central spot of the frame and can be very useful in shooting wildlife to ensure detail of specific body parts. Center-weighted metering takes a light reading from the entire frame, but 75% of the priority is given to the center of the frame. The book also goes over the three basic exposure modes: aperture priority mode, shutter priority mode, and manual mode. Aperture priority allows the user to set his/her desired aperture while the camera decides a suitable shutter speed. Shutter priority allows the user to set his/her desired shutter speed while the camera decides a suitable aperture. Manual allows the user to set both aperture and shutter speed.
The second section in part two gives a few tips on reading light in different situations. It is generally accepted that the midday sun gives the most harsh light and is not conducive to picture taking. Front light refers to the light being positioned behind you. This type of lighting is recommended when you wish to portray saturated color and contrast, and it can be used in early or late day. Sidelight refers to the light coming from the side of the frame. "Sidelight produces long, deep shadows that reveal the wrinkles, dimples, ridges and other details of a surface in greatest relief." Backlight refers to the light being directly behind the subject in a photograph. It has the most dramatic effect on subjects with fur or feathers where the light can shine through and show high contrast. Sunset flash, which is just the use of natural light at either sunset or sunrise, is unique in that it allows for colorful soft light to be projected onto the subject. Electronic flash, which is the use of artificial light, delivers harsh and many times undesirable light to the subject, but can be properly used to shoot small animals with lots of depth of field.
I have always been interested in pictures that illustrate motion. Prerequisite to developing these shots is making sure the camera is secure (tripod recommended). A good rule of thumb to shooting these photos is to set the shutter speed no slower than the inverse of the lens' focal length. If you are looking to freeze the motion of something quickly coming towards the camera, a moderate shutter speed (around 1/125) would allow most of the shot to be frozen, while some motion could be blurred. If shooting a subject that is moving laterally across the frame, a much faster shutter speed may be required depending on how much the subject is magnified (greater shutter speed for more magnification). Panning the camera can be useful in reducing subject blur while the background is smoothly blurred. If a bird is flying laterally, you can pan the camera and get most of the bird in focus while the background is blurred.
Modifying natural light is sometimes necessary to improve definition, color, reduce glare, or make light to dark in-frame transitions less harsh. When looking for filters, it is best to get ones that will fit your biggest diameter lens. Polarizing lenses produce greater color saturation or eliminate reflective glare from non-metallic surfaces such as leaves, grass, and water. They reduce scene brightness by one or two stops. Split neutral density filters, which are half clear and half neutral density tint gray. They can be used in high contrast landscape situations when the sky is much brighter than the terrain. Graduated neutral density filters accomplish a similar goal as split neutral density filters, except the frame contrast may be less abrupt between light and dark. Graduated neutral density filters are gradually tinted from clear to neutral density gray. Standard neutral density filters can be used in extremely bright situations where the camera normally would not be able to take the shot. Blue/gold polarizing filters, like other polarizing filters, alter light only from reflected surfaces. They are used to reduce glare, bump up color saturation on land and water, and boost sky color and density.
Finally, designing the picture space is a crucial part to shooting any picture. It does not matter how good of a job you have done in getting proper exposure or properly manipulating the light if the frame is not composed in an interesting way. Establishing visual priorities is just based on the shooter's thoughts of what he/she is interesting. The book talks about some general visual priority thoughts: "red is more attractive than yellow; large draws more attention than small; difference draws more attention than conformity; jagged lines are more striking than curved ones; diagonal lines are more attractive than vertical ones; sharpness is more attractive than blur; and light is more attractive than dark. The rule of thirds is also an important concept in frame composition. It states that the center of interest should be placed one-third of the way from the top or bottom of the frame and one-third of the way from either side.
Citations:
Fitzharris, Tim. National Audubon Society Guide to Nature Photography Digital Edition. Buffalo: Firefly, 2008.
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